The present invention relates to a method for mounting parts by means of conductive paste, and an IC card and its manufacturing method.
In manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, coils such as a copper wire-wound coil, coils of printed conductive pastes, e.g. silver paste, and coils of etched metal foils, e.g. copper foil, are used as a coil, and in particular, a method for forming a circuit pattern by printing conductive pastes has become popular.
FIGS. 10 to 13 show a conventional IC card and its manufacturing method.
As shown in FIG. 10, the conventional IC card is constructed such that a coil pattern 2 is formed on the first substrate 1a by means of a conductive paste, and a connecting pad 6 provided at the external end 3a of this coil pattern 2 and a connecting pad 6 provided at the internal end 3b are electrically connected with electrodes of an IC chip 4.
The manufacturing process is shown in FIG. 11.
Firstly, in step 1, a circuit pattern including the coil pattern 2 is printed on the surface of the first substrate 1a by means of the conductive paste.
In step 2, the printed circuit pattern is heated for 10 minutes at the temperature of 120xc2x0 C. to cure the conductive paste.
In step 3, as shown in FIG. 12(a), an anisotropic conductive sheet 9 is stuck on the connecting pad 6 of the circuit pattern.
In step 4, the anisotropic conductive sheet 9 is heated for 5 seconds at the temperature of 100xc2x0 C. and temporally pressed.
In step 5, parts such as the IC chip 4 and capacitors are mounted on the temporally pressed anisotropic conductive sheet 9.
A bump 10 is formed on an mounting surface of the parts 16 via an electrode pad 7, as shown in FIG. 12(b), and the bump 10 is electrically connected with the connecting pad 6 via the anisotropic conductive sheet 9, as shown in FIG. 12(c).
Particularly, the IC chip 4 is placed such that, as described above, the connecting pads 6 provided at the external end 3a and the internal end 3b of the coil pattern 2 are electrically connected with the electrode pad 7 of the IC chip 4.
And, the bump 10, formed by using wire bonding and plating, in particular, plating using solder, gold, silver, and copper is used.
In step 6, the anisotropic conductive sheet 9 is heated for 30 seconds at the temperature of 200xc2x0 C. to be cured for pressing the parts 16 as shown in FIG. 12(d).
Then in step 7, by applying a second substrate to the first substrate 1a for laminating processing, as shown in FIG. 13, the IC card can be obtained in which the connecting pads 6 and the bump 10 provided on the parts 16 are electrically connected via the anisotropic conductive sheet 9. 5 denotes a capacitor connected in parallel to the coil pattern 2, and 1b denotes the second substrate.
However, since it is typical to use inexpensive thermoplastic resin such as polyethylene terephthalate and vinyl chloride for the first substrate 1a and the second substrate 1b, there is a problem that, in the conventional manufacturing process described above, these substrates having less heat resistance are susceptible to degradation due to the high temperature of 200xc2x0 C. or more when pressing the anisotropic conductive sheet 9 in step 7.
Also, there is a problem that using a substrate having superior heat resistance instead of the thermoplastic resin increases the costs.
And there is a further problem that the connecting resistance and the number of steps are increased, and the productivity is lowered, and costs are increased because the anisotropic conductive sheet is used for securing the parts. And it is the same with the case of using an anisotropic conductive particle instead of the anisotropic conductive sheet.
And, when the parts 16 are mounted in step 5, there is a problem that it is needed to draw a plurality of coil patterns 2 between the terminals of the IC chip 4, as shown in FIG. 10, since the external end 3a and internal end 3b of the coil pattern 2 are constructed not so as to be linked to each other in a single brush stroke.
The present invention provides a method for mounting parts, and an IC card and its manufacturing method, that is capable of solving the problems, reducing the number of steps, increasing the productivity to lower costs, and miniaturizing the chip.
To solve the problems, the method for mounting parts according to the invention is characterized in that parts to be mounted are placed on the circuit pattern before the conductive paste is cured, and then mounted by curing the conductive paste.
According to the invention, it is possible to lower costs due to the reduction of steps, the good productivity, and the possibility of the low temperature mounting of the parts, and further to contribute to the miniaturization of the IC chip.
The method for mounting parts according to a first embodiment of the invention is characterized in that a circuit is formed by printing a circuit pattern on a substrate by means of a conductive paste, placing parts on the circuit pattern such that its electrode is connected to the circuit pattern, and curing the conductive paste to electrically connect the electrode with the circuit pattern.
According to this configuration, it is possible to mount parts at low temperatures and reduce steps to lower costs.
The method for mounting parts according to a second embodiment of the invention is characterized in that a circuit is formed by printing a circuit pattern on a substrate by means of a conductive paste, placing parts having a pump formed on its electrode pad on the circuit pattern such that its electrode is connected to the circuit pattern, and curing the conductive paste to electrically connect the electrode to the circuit pattern.
The method for mounting parts according to a third embodiment of the invention is characterized in that the bump is formed of metals or plating.
The IC card according to a fourth embodiment of the invention is a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, and is characterized in that a first electrode of the IC chip for processing signals received from the coil is connected to an internal end of a coil pattern formed on the substrate, and an external end of the coil pattern and a second electrode of the IC chip are connected via a jumper wiring means.
According to this configuration, it is possible to reduce manufacturing steps and lower costs, by directly mounting parts on the conductive paste before it is cured, and then by curing the conductive paste, and it is possible to stabilize the circuit pattern, as well as ensure an electrical connection between the circuit pattern and the parts.
And, an anisotropic conductive sheet is not required to provide, and it becomes possible to various parts at low temperature, and also lower resistance can be realized.
And further, it is not required to draw a plurality of coil patterns between the terminals of the IC chip, so that it is possible to use an IC chip having narrow space between the terminals to miniaturize the IC card.
The IC card according to a fifth embodiment of the invention is characterized in that the jumper wiring means is a wire having an insulatingly covered middle portion and ends with exposed conductive portions, or a foil constituted of an insulating sheet with a metal film.
The method for manufacturing the IC card according to a sixth embodiment of the invention is characterized in that, in manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, it comprises the steps of printing the circuit pattern including the coil pattern on the substrate by means of the conductive paste, placing the IC chip on the circuit pattern such that its electrode is connected to the circuit pattern, placing the jumper wiring means for connecting over the coil the electrode pad at the external end of the coil to the electrode pad drawn out of the IC chip or a signal line to the IC chip before the conductive paste is cured, and curing the conductive paste.
According to this configuration, it becomes possible to miniaturize the IC card.
The method for manufacturing the IC card according to a seventh embodiment of the invention is characterized in that, in manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, it comprises the steps of printing the circuit pattern including the coil pattern on the substrate by means of the conductive paste, placing the IC chip on the circuit pattern such that its electrode is connected to the circuit pattern, and after the conductive paste is cured, placing the jumper wiring means for connecting over the coil the electrode pad at the external end of the coil to the electrode pad drawn out of the IC chip.
The method for manufacturing the IC card according to an eighth embodiment of the invention is characterized in that the jumper wiring means is configured by printing a pattern, which links the electrode pad at the external end of the coil and the electrode pad drawn out of the IC chip, by means of insulating ink at the portion of the coil across the jumper wiring means, and printing conductive ink over the pattern.
According to this configuration, it is possible to make the IC card thinner, and improve the productivity due to its short drying time.
The method for manufacturing the IC card according to a ninth embodiment of the invention is characterized in that, in manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, it comprises the steps of printing the circuit pattern including the coil pattern on the first substrate by means of the conductive paste, placing the IC chip on the circuit pattern such that its electrode is connected to the circuit pattern and curing the conductive paste, printing the conductive paste at the position corresponding to the portion in the second substrate laminated on the first substrate which connects the electrode pad at the external end of the coil and the electrode pad drawn out of the IC chip over the coil formed on the first substrate to form the jumper wiring means, applying this second substrate to the first substrate, with an insulating film which has communicating openings formed at the positions corresponding to the electrode pad at the external end of the coil and the electrode pad drawn out of the IC chip being interposed, curing the conductive paste, and connecting the electrode of the first substrate and the conductive paste of the second substrate.
The method for manufacturing the IC card according to a tenth embodiment of the invention is characterized in that, in manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, it comprises the steps of printing the circuit pattern on the substrate by means of the conductive paste, placing the IC chip on the circuit pattern before the conductive paste is cured such that its electrode is connected to the circuit pattern, curing the conductive paste, and electrically connecting each end of the coil constituted of a wound line to the circuit pattern.
The method for manufacturing the IC card according to an eleventh embodiment of the invention is characterized in that, in manufacturing a non-contact IC card comprising a coil and an IC chip, and transferring data with external via the coil, it comprises the steps of printing the circuit pattern on the substrate by means of the conductive paste, placing the IC chip on the circuit pattern before the conductive paste is cured such that its electrode is connected to the circuit pattern, placing each end of the coil constituted of a wound line on the circuit pattern before the conductive paste is cured, and curing the conductive paste.